As a conventional radioactive ray detector module is disclosed, for example, in the following the Patent Document 1, a semiconductor detector module, having semiconductor elements for generating signal inductive charges upon receipt of radioactive rays thereon, and a pair of electrodes, being provided so as to put said semiconductor element therebetween, thereby obtaining a data signal due to an incidence of the radioactive rays upon said semiconductor element, and wherein a partial insulating, being disposed between other electrode neighboring with and having an area smaller than that of the pair of electrodes mentioned above, is provided at least on one of said pair of electrodes.
When trying to align/dispose the semiconductor detector modules to be dense or crowded, for increasing a positional resolving power of radioactive ray detection, normally, an electrically insulating layer is put between the electrode of one of the semiconductor elements neighboring with and the electrode of the other one thereof, for maintaining the electrical insulation between the semiconductor elements of the semiconductor detector modules neighboring with each other. In this instance, since the electrodes of the semiconductor elements neighboring with are so disposed that they face to each other while putting the electrically insulating layer therebetween, there is generated a parasitic capacity due to those electrodes and the electrically insulating layer. On the contrary to this, the semiconductor detector module described in the following Patent Document 1 is provided with an insulator having small area, at least on one (1) of the electrodes, and with this, it is said that the parasitic capacity can be reduced by lowering a dielectric constant between the electrodes.